JP2990659B2 - Single crystal pulling device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulling apparatus for producing a single crystal by the Czochralski method (hereinafter, referred to as "CZ method"). The present invention relates to a single crystal pulling device that can be safely pulled up without dropping.

[0002]

2. Description of the Related Art There are various methods for producing a single crystal. Among them, the CZ method is widely applied in a method capable of industrial mass production for growing a silicon single crystal.
The production of a single crystal by this method involves bringing a seed crystal into contact with the surface of a melt of a crystal raw material contained in a crucible, rotating the crucible, and pulling the seed crystal upward while rotating the seed crystal in the opposite direction. Thereby, a single crystal in which the melt is solidified grows at the lower end of the seed crystal.

When a single crystal is produced by the CZ method,
When the seed crystal is brought into contact with the melt, it is necessary to completely remove dislocations generated by the thermal shock so as not to reach the single crystal body. Usually, as this measure, in order to eliminate dislocations from the crystal surface and make the single crystal dislocation-free,
A so-called "dash neck processing" for narrowing the diameter into an elongated shape is employed. At this time, the diameter of the dashes neck necessary for eliminating dislocations is about 3 mm, and its length is required to be 30 mm.

Conventionally, the weight of a single crystal manufactured by the CZ method has been limited to about 20 to 30 kg. However, in recent years, there has been a strong demand for more efficient semiconductor manufacturing. And the weight of the single crystal is 100 kg
In many cases. The weight of the single crystal is borne by the narrowed dash neck portion. However, as described above, even if the weight of the manufactured single crystal increases, the load that can be borne is limited. If the single crystal becomes too heavy and torsional or bending stress is applied during pulling, the dash's neck of the single crystal will break, and the single crystal will fall into the melt in the crucible, further damaging the pulling equipment. , Outflow of molten liquid, explosion of steam, etc. may occur, leading to personal injury.

Therefore, an improved pulling device has been proposed for the purpose of preventing an accident such as a drop during pulling which is expected to occur frequently with an increase in the weight of a single crystal (FIG. 1). For example, JP-A-3-285893, JP-A-3-285893
295893). That is, by forming an engaging step on the upper part of the single crystal and adopting a structure in which the engaging step is engaged and gripped by a plurality of claws or a plurality of grip holders having claws, The single crystal is prevented from falling. For this reason, the use of the proposed pulling apparatus makes it possible to pull up a single crystal reliably and safely even when pulling a heavy single crystal.

[0006]

In the lifting apparatus disclosed in Japanese Patent Application Laid-Open Nos. 3-285893 and 3-295893, as described above, the engaging step formed on the single crystal is formed by a claw,
Alternatively, a gripping holder having claws is engaged and gripped. At this time, eliminating a deviation between the center position of the pulled single crystal and the pulling axis is an important management item in terms of quality.
Therefore, in the above-described lifting device, a plurality of claws or a plurality of grip holders are provided as a countermeasure for them, and a positional shift is eliminated by fine adjustment of each nail or the grip holder,
Engagement and gripping at the engagement step portion is ensured.

However, since the pulling of the single crystal is performed in a closed vacuum chamber, the operation of the claw or the gripping holder must be controlled from the outside so as to match the engaging step of the single crystal which is constantly rising and rotating. It is very difficult to fine-tune by remote control. Therefore, the adjustment of the position where the engagement step portion is engaged and gripped tends to be inconvenient, and once a displacement occurs, not only does the quality of the pulled single crystal significantly deteriorate, but also the single crystal is pulled during the pulling. In addition, the single crystal may be greatly inclined due to the torsion, and the nail or the grip holder may be disengaged to drop the single crystal.

SUMMARY OF THE INVENTION The present invention solves the above-described problems of the conventional pulling apparatus, and ensures engagement and gripping at an engaging step provided on a single crystal, thereby achieving a heavy weight single crystal. It is an object of the present invention to provide a single crystal pulling apparatus which can appropriately manufacture a single crystal without causing a fall accident even when pulling a single crystal and is excellent in safety.

[0009]

The present invention, as shown in FIG. 1, has the following single crystal pulling apparatus.

That is, the main pulling means 23 for forming the inverted conical engaging step 6 in the single crystal 3 which is pulled while being rotated, the holding mechanism 11 for gripping the single crystal, and the main pulling means A single crystal pulling apparatus comprising a sub pulling means 24 for raising the holding mechanism in synchronization with a pulling speed, wherein the holding mechanism has a push rod which moves up and down at a predetermined lifting position as the lifting mechanism moves. 16 and the single crystal engaging step 6
And an engaging member 13 for engaging and gripping the single crystal.

Here, an "engaging member" provided on the holding mechanism is provided.
As shown in FIG. 1 and FIG. 4 described later, the holding lever 14 and the rotating lever 15 are integrally formed, and the tip of the rotating lever 15 is in contact with the push rod 16.

In the above lifting device, the main lifting means
It is desirable that the 23 and the sub-raising means 24 can be independently raised and lowered by winding and unwinding the wire, and the sub-raising means 24 should raise and lower the holding mechanism 11 via the inclination preventing means 18 of the holding mechanism. This is because the inclination of the holding mechanism 11 is eliminated, and a stable pulling operation and an improvement in the quality of the single crystal can be achieved.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In a single crystal pulling apparatus of the present invention, a seed crystal is brought into contact with a melt surface by a main pulling means, pulled up while rotating, and subjected to a dashes neck treatment. After the engagement step is formed, the shoulder is formed and the single crystal body is pulled up. On the other hand, the weight of the single crystal increases with the progress of pulling, but before reaching the limit of the load that can be borne by the dash neck portion, the process shifts to holding the single crystal by the sub pulling means.

As a specific operation, the holding mechanism, which has been waiting above, is lowered by the lowering operation of the sub pulling means. At the time of this lowering, the push rod provided at the lower end of the holding mechanism is pushed up by the single crystal shoulder at a predetermined position and moves up. By this ascent operation, the rotating lever of the engaging member that is in contact with this is pushed up, and the holding lever pivots to engage the engaging step of the single crystal. Since the receiving surface of the holding lever that has been turned and closed has a continuous ring shape, the single crystal can be securely engaged and gripped.

When the engagement and grip of the single crystal by the holding lever of the holding mechanism is completed, the holding mechanism is raised by synchronizing the pulling speeds of the main pulling means and the sub pulling means. At this time, in order to eliminate the inclination of the holding mechanism, it is desirable to attach an inclination preventing means such as an equalizer.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a single crystal pulling apparatus according to the present invention.

FIG. 1 is a longitudinal sectional view for explaining an example of the overall configuration of the apparatus of the present invention. As shown in FIG. 1, a crucible 1 is provided at a central position in a vacuum chamber (not shown), and a melt 2 in which polycrystalline silicon as a raw material is melted is held therein. Seed crystal holder above crucible 1
10, a holding mechanism 11 is disposed, and further provided above the main pulling means 23 as means for pulling up the silicon single crystal 3 while rotating it, and a sub-pulling means 24 as means for raising and lowering the holding mechanism 11 are provided. , These constitute a lifting mechanism 22.

In the apparatus of the present invention, the main pulling means 23
One main wire 20 wound by the sub-raising means 24 and two main wires 21
And these are independently lifted and lowered. The pulling mechanism 22 composed of the main pulling means 23 and the sub pulling means 24 is rotated in a predetermined direction by a structure (not shown) to rotate the single crystal at a constant speed in the pulling step.

At the lower end of the main wire 20, a seed crystal holder 10 is attached.
The holding mechanism 11 is disposed at the tip of the holding mechanism 11 via an equalizer 18. The equalizer 18 used here functions as a means for preventing the holding mechanism 11 from tilting.

FIG. 2 is a cross-sectional view of the holding mechanism and the equalizer indicated by arrows AA in FIG. Reference numeral 12 in the figure denotes a holding holder that forms the appearance of the holding mechanism. The equalizer 18 is supported by the holding holder 12 via a pin 19 and is vertically provided by two sub-wires 21. By adopting such a structure, even if there is a difference in the winding of the two sub wires 21, the
Although 18 tilts, the holding mechanism 11 is not affected. Therefore, the single crystal can be reliably held by the holding mechanism 11 without the center axis of the holding mechanism 11 being displaced from the center axis of the single crystal 3.

FIG. 3 is a plan view for explaining an example of the structure of an engaging member provided in the holding mechanism shown by the arrow BB in FIG. As is clear from FIGS. 1 and 3, the engaging member 13 is integrally formed by the holding lever 14 and the rotating lever 15. The engagement member 13 is rotatably attached to the lower end of the inner surface of the holding holder 12, and the holding lever 14 is opened from a vertical state to a horizontal state about a fulcrum on the holding holder 12 side. You can turn 90 degrees until

FIG. 4 is a view for explaining an operation in which the engaging member turns as the holding mechanism descends. As mentioned above,
Before the limit of the load that can be borne by the main pulling means 23 is reached, the holding mechanism 11 waiting above is lowered by the lowering operation of the sub pulling means. During this lowering, after the large-diameter portion 7 formed in the engagement step portion of the single crystal passes through the lower end of the holding mechanism 11, the push rod 16 provided at the lower end of the holding mechanism 11 moves the single crystal shoulder 4 It is pushed up and rises. Due to the upward movement of the push rod 16, the rotating lever 15 in contact with the push rod 16 is pushed up, and the holding lever 14, which is integrally formed, pivots and closes to engage the engaging step of the single crystal. The closed holding lever 14 is supported by a stopper 17 and forms a fixed opening hole diameter as shown in FIG. The diameter of the opening hole is smaller than the large diameter portion of the single crystal, and the receiving surface of the holding lever has a continuous ring shape. Therefore, once the holding lever is closed, there is no fear of disengagement. Even if there is a dimensional deviation in the engagement step portion of the single crystal, it can be securely engaged and gripped.

In the apparatus according to the present invention, the engaging member 13 is constituted by the holding lever 14 and the rotating lever 15, so that when the rotating lever 15 makes a turn of about 30 ° by pushing up the push rod 16 from the horizontal state, the engaging member is engaged. Joint material
The position of the center of gravity of 13 changes, and thereafter the turning is continued by its own weight, and the holding lever 14 shifts to the closed state. When the holding lever 14 is in the closed state, the receiving surfaces of the holding lever gather to form a ring-shaped holding surface.

Although the number of the engaging members provided on the inner circumference of the holding holder 12 is four in FIG.
It is not limited to this as long as a ring-shaped holding surface can be formed.

Next, a specific operation procedure will be described. At the time of starting the pulling of the single crystal, the sub pulling means 24 stands by while holding the holding mechanism 11 upward. On the other hand, the seed crystal 9 is attached to the seed crystal holder 10 provided at the tip of the main pulling means 23, and this seed crystal 9 is brought into contact with the center of the liquid surface of the silicon melt 2. Thereafter, the main pulling means 23 is operated to slowly raise the seed crystal 9 while rotating the seed crystal 9, thereby forming a dash neck (seed drawing portion) 8. Next, the diameter of the single crystal is increased by slowing down the pulling speed of the single crystal to form a large-diameter portion 7, and then the diameter of the single crystal is gradually reduced and narrowed down to the constricted portion 5, and the cross-sectional shape is inverted conical. An engaging step 6 is formed.

After forming the engaging step 6, the shoulder 4 is formed by increasing the diameter of the single crystal again, and thereafter, the pulling speed and the rotation speed are adjusted to the steady conditions to adjust the single crystal body 3 having a predetermined diameter. Move to lifting.

When the weight of the single crystal to be pulled reaches a certain weight after the transition to the steady single crystal pulling, for example,
When the length of the single crystal body 3 becomes 1 m, the holding mechanism 11 waiting above is lowered. In the descending stage, as described with reference to FIG. 4, the holding lever 14 is allowed to pass through the large diameter portion 7 of the single crystal in the open state, and thereafter, by the action of the push rod pushed up by the single crystal shoulder 4, The holding lever 14 is closed.

After the engaging step 13 of the single crystal is engaged and gripped by the engaging member 13 of the holding mechanism 11, the sub-pulling means 24 is synchronized with the pulling speed of the main pulling means 23. Raise 11

Here, the holding mechanism 11 is lifted by holding the single crystal by the holding lever 14 as an engaging member after the weight of the single crystal reaches a certain weight, that is, at least in the pulling step. The second half is sufficient.

When the holding mechanism 11 is raised by synchronizing the main pulling means 23 and the sub pulling means 24, the main pulling means 23
It is preferable that the main motor 25 is controlled by a speed control and the sub motor 26 of the sub pulling means 24 is controlled by a torque.

By employing such a control method of the pulling drive motor, the weight of the single crystal can be shared by the holding mechanism of the sub pulling means. Therefore, interference between the control systems of the pulling drive motors can be prevented, the pulling speed and the load ratio between the main motor and the sub motor can be accurately controlled, and stable single crystal pulling without shock can be achieved.

[0032]

According to the single crystal pulling apparatus of the present invention, it is possible to secure the engagement and gripping at the engaging step provided on the single crystal and to pull a heavy single crystal. However, a single crystal can be safely manufactured without a fall accident. Moreover, it can be applied with a simple device, and does not require a large facility cost.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating an example of the overall configuration of a device of the present invention.

FIG. 2 is a cross-sectional view of the holding mechanism and the equalizer indicated by arrows AA in FIG.

FIG. 3 is a plan view illustrating a configuration example of an engagement member provided in a holding mechanism indicated by arrows BB in FIG. 1;

FIG. 4 is a view for explaining an operation in which an engagement member turns as the holding mechanism descends.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Crucible, 2 ... Melt, 3 ... Single crystal body 4 ... Single crystal shoulder, 5 ... Constricted part 6 ... Engagement step part, 7 ... Large diameter part 8 ... Dashes neck (seed drawing part) 9 ... Seed crystal , 10 ... seed crystal holder 11 ... holding mechanism, 12 ... holding holder 13 ... engaging member, 14 ... holding lever 15 ... rotating lever, 16 ... push rod 17 ... stopper, 18 ... ecolizer 19 ... pin, 20 ... main wire , 21 ... sub wire 22 ... pulling mechanism, 23 ... main pulling means 24 ... sub pulling means, 25 ... main motor 26 ... sub motor

Claims (2)

(57) [Claims] 1. A main pulling means for forming an inverted conical engagement step on a single crystal which is pulled while being rotated, a holding mechanism for gripping the single crystal, and a pulling speed of the main pulling means. What is claimed is: 1. A single crystal pulling device comprising a sub-pulling-up means for raising said holding mechanism in synchronism, wherein said holding mechanism includes a push rod which moves up and down at a predetermined raising and lowering position as said lifting mechanism moves up and down. A single crystal pulling device provided with an engaging member which is turned by the ascending operation of the above and engages and grips the engaging step of the single crystal. 2. The main pulling means and the sub pulling means can be independently raised and lowered by winding and unwinding a wire.
2. The single crystal pulling apparatus according to claim 1, wherein the sub-pulling means raises and lowers the holding mechanism via a tilt preventing means of the holding mechanism.